The present invention relates to a driving force transmission device that distributes a driving force of an engine, for example, to the rear wheel side and controls the distribution.
A driving force transmission device transfers a torque between one drive shaft and the other drive shaft (hereinafter also referred to as “two members”) by engagement of a multiple disk clutch disposed in a filled area of lubricating oil, as described in JP-A-2002-340053 (patent document 1). And an engagement force of the multiple disk clutch is adjusted by controlling an energizing current to an electromagnet.
In such driving force transmission device, even if the energizing current for the electromagnet is controlled based on the same transfer torque command value, the transfer torque between two members for transferring the driving force is changed due to a change with the passage of time. Thus, noting that the temperature characteristic of lubricating oil is varied due to a change with the passage of time, the optimal correction command value is calculated corresponding to a change with the passage of time by updating the transfer torque characteristic at the maintenance time, as described in patent document 1. The transfer torque command value can be corrected with the calculated correction command value to prevent influence due to a change with the passage of time.
Also, in consideration of a change in the clutch engagement force due to a change with the passage of time, the clutch engagement force is corrected so that an actual rotational speed difference between one drive shaft and the other drive shaft may be matched with the ideal rotational speed difference, as described in JP-A-2002-12049 (patent document 2).
[Patent document 1] JP-A-2002-340053
[Patent document 2] JP-A-2002-12049